1. Everything in the physical universe is deterministic, i. e. caused, i. e. related to the rest of the physical universe.
2. Knowing all the causes, the effect is necessarily known.
3. Not knowing all the causes, possible causes are tried (tested). This is basically an heuristic process.
4. What is a cause is a different question of how is that a cause interact so as to provoke an effect. Determining what is a cause is forecasting. Determining how is that a cause interact is explaining.
5. Not knowing the total logic of a cause-effect relation, i. e. not being able to fully explain a cause-effect relation (including but not limited to not being able to fully forecast the full list of causes which provoke an effect), possible causes are tried (tested). This process of finding provisional hypothesis is basically an heuristic process.
6. An heuristic theory cannot be accepted, i. e. cannot be taken as a complete explanation of some effect. An heuristic theory can only be failed to be rejected in the sense of being unable to find an obvious contradiction. It takes only an asserted contradiction to reject an heuristic hypothesis.
7. A heuristic theory calls for statistic inferential tests as the process to determine its definite rejection or its everlasting provisional failure to reject it.
8. An explanation is a logical structure which if free from logical errors cannot be contradicted by reality. Due to the complex nature of the reality far beyond of human ability to explain (or the totality of reality is explained or not), explanations are only mental logical structurizations.
9. A structure or model is a logical structurization in which the effects are fully explainable through the causes.
10. A model can only be proved wrong through finding a logical error. It can never be proved wrong through empirical testing.
11. In the aim of reality only particular explanations are possible. The study of reality is always the study of concrete episodes, it is history.
12. A model can be used to advance an understanding of an empirical, i. e. historical or real, phenomenon even if the full exhaustive explanation of reality is impossible.
13. An exhaustive explanation of reality would be an explanation of all reality, through all times and all spaces. It would include, but wouldn't be limited to, the reduction of mental phenomena to physical phenomena. Given that the very cerebral process which would aspire to such an explanation would of need require physical changes in the process of explaining, that would create a loop to eternal development of explanation which, under the physical limitations of human nature are not just technological but logically impossible.
14. In order to use a model to advance the understanding of specific aspects of reality, an identification of the model's concepts with heuristically defined aspects of reality must to be achieved. An example in economics would be the identification of the concept of agent with a specific human being, for instance. The question of whether a regular adult, or child, or an idiot, or a baby, or the most intelligent animal in the world, or a regular dog, or a mouse, or a roach, or a bacteria, or a molecule, or a plant, or a piece of wood, or a chair, or an office, or a factory or the state, or a religion, or the universe is an agent or not, is at the end an heuristic decision whose appropriateness depends, in science, of its power to advance understanding, whose appropriateness in advance, depends, in technology, of its power to allow the assembly of inventions which work.